Mechanical movement



March 10, 1942. v H. VAN SANT I 2,276,003

MECHANICAL MOVEMENT Filed July 22, 1939- Patented Mar. 10, 1942 MECHANICAL MOV EMENT Victor H. Van Sant, West-field, N. J., assigner to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application July 22, 1939, Serial N0. 285,842

2 Claims.

This invention relates to a mechanical movement, and more particularly to a device for converting rotary motion into reciprocatory motion.

In those arts which deal with materials in strand form, e. g. threads, wires, laments and the like of all kinds, there are countless situations where a strand is to be wound in even successive layers upon some kind of spool, reel, tube, rod, or other core member. Particularly where electrical conductor strands are to be wound in coiled layers upon a core for innumerable applications in the electrical arts it may be of prime importance that the successive turns of the strand being wound on a core be laid with a predetermined and unvarying pitch of the helix formed by the strand, Whether the coils are laid on in close juxtaposition or spaced more or less widely from each other along each layer. It is customary in many instances of coil winding apparatus to rotate the core to be wound about its axis while the strand to form the co-il winding is fed to the rotating core through a guide member which is caused to move with a reciprocating linear motion parallel to the axis of rotation of the core. The necessary and sufficient conditions to obtain uniformity of winding then comprise two principal features, rst that the ratio of the rotary speed of the core to the linear speed of the strand guide shall be contsant, and, second, that the reversals of direction of the reciprocating strand guide shall be instantaneous.

An object of the present invention is to provide a mechanical movement for converting rotary motion into reciprocating motion such that the ratio of the speeds of the two motions shall be substantially constant and the reversals of the reciprocation shall be substantially instantaneous.

One embodiment of the invention may present a rotatable cam member having its cylindrical periphery provided with a cam track formed as a sunken groove or as a protruding ridge extending around the cylinder in matched halves of one right and one left hand helical turn of equal pitch, in combination with a block shaped to match a cross section of the cam track.

Other objects and features of the invention will appear from the following detailed description of an embodiment thereof taken in connection with the accompanying drawing in which the same reference numerals are applied to identical parts in the several figures and in which Fig. l is a plan view of a mechanical movement constructed in accordance with the invention;

Fig. 2 is a view thereof in end elevation;

Fig. 3 is a detached view in perspective from below of the cam block;

Fig. 4 is a detached view in perspective of one of the split cam plugs;

Fig. 5 is a View on a smaller scale of the device of Fig. 1 as used to drive a strand distributor;

Fig. 6 is a perspective view of a modified form of cam and block;

Fig. 7 is a detached view in perspective from below of the cam block of Fig. 6; and

Fig. 8 is a diagrammatic representation of another form of cam body.

1n the embodiment of the invention disclosed in Figs. l to 5 inclusive, a cylindrical cam body 20 is mounted on a coaxial shaft 2l by means of keys 22. A cam groove 3i) extends in a closed loop about the cam body in the periphery thereof and is formed in two parts. The upper part extending from the right rear (Fig. l) upwardly over the body and downwardly to the left front is essentially one half of one full turn of a left hand helix. The under part of the cam groove is an exactly symmetrical half of one full turn of an equal right hand helix. .Preferably the lateral walls 3l, 32, 33 and 34 of the cam grooves are generated by a segment of a radius of the cylinder, so that these walls are everywhere perpendicular to the outer cylindrical surface, in other words, so that the groove is' composed of two half turns of square screw threads of opposite hand. The continuous floor of the groove is part of one continuous cylindrical surface.

A cam block 40 is formed to lit the groove or track 30. Its respective faces 4I, 42, 43 and 44 are shaped to have identical curvatures with the respective walls 3|, 32, 33 and 34 of the track, and its under face matches the cylindrical bottom or floor 35 of the track. The top surface 41 of the block may have any contour and is here shown as flat. A tapped hole 46 extends through the center of the block radially of the body 20 to provide for attaching the block to any member to be moved thereby.

Thus in Fig. 5, a lug 5I formed on a bar 5i) is secured to the block 40 by a screw 52. The bar 50 is slidably mounted in suitable supports 53 to be reciprocable parallel to the axis of the shaft 2 l. A guide sheave 54 carried by the bar 50 is thus adapted to be used to distribute a strand (not shown) passing over it with a constant to and fro advance, if the shaft 2| be driven at a constant speed of rotation as by gearing 48, 49 from any power source not shown.

The cam track 30, as described, consists of two helical portions exactly alike except that one is right and the other left hand. Assuming that the shaft 2| and hence the cam body 20 are being driven in the direction of the arrows in Figs. 1 and 2 at a constant speed of rotation, the cam block 40 will be forced to move to the right between the walls 33 and 34 of the lower half of the cam track, until the block reaches the right hand angular part of the track. Here it is substantially instantaneously stopped by the wall 3| and reversed in motion and carried back toward the left between the walls 3| and 32. This reversal, which occurs alternately at both anglesV of the track, is described as substantially instantaneous. It cannot be truly instantaneous because of the theoretically innitely great decelerations and accelerations involved in such a case with consequent innite stresses. But, if the parts involved are suii'iciently light, strong, hard and resilient the effect is substantially an instantaneous reversal, and irregularities in a coil Wound in this manner are found to be negligible.

If such a track as is shown in the structure now being considered were to be out in a solid cylinder, it would be an impracticable construction, since the angles especially of the track would have to be cut by hand.

In order to make it possible to cut the track 30 by machine tools, a cylindrical hole 23, not less in diameter than the diagonal dimension of the block 40, is bored radially into the cylindrical body enclosing the site of one angle of the cam track. Two double plugs 24, 25 are made each in the form of a longitudinally centrally divided cylinder having a drive t in the recess 23. A similar pair of double plugs is made for the other angle of the track. One double plug of each pair is seated in the hole in which it belongs and locked in place by a pin 26 seated in a bore 21 formed partly in the plug and partly in the body.

The upper half 3|, 32 of the cam track may now be cut with a suitable machine tool, reducing the plug half 24 from the half cylinder shown in partially dotted outline in Fig. 4 to the formshown there in full outline. But the wall 33 of the plug half 25 of Fig. 4 will be cut away and spoiled by the tool. However, the half 24 is now produced as it should be. Both halves are removed, and the half 25 discarded. The second double plug is then set into the recess 23 and the lower half 33, 34 of the cam track is cut in similar fashion. This produces one perfect half plug 25 and one spoiled half plug 24. The latter is discarded and the two perfect half plugs are set in place. The corresponding operations are performed simultaneously at the other angle of the track, thus producing the completed track. For convenience in removing the plugs 24, 25 from the recesses 23, an aperture 28 may be bored through the body 20 coaXially with each recess.

The structure shown in Figs. 6 and 7 is a modified form of device embodying substantially the same principles. Here the cam track |30 is a rib standing up from the cylindrical surface of the body |20 and the block |40 straddles the track by means of appropriately shaped lugs on which are formed the faces |4|, |42, |43, |44 which cooperate respectively with the walls |3|, |32, |33, |44 of the rib |30. Here again a component of the body (in this case the whole body instead of an inset plug) is split along a plane passing through the vertex of an angle of the track, in order that the track may be cut by machine tools. The two parts of the body are held together in any suitable manner such as by bolts 29.

In each of the structures disclosed, the cam track is essentially a loop composed of two half turns of helices of equal right and left hand pitch respectively. From this it results that the two and fro motions of the block in each instance are equal in speed. If, however, one side of the loop extends more than halfway around the body, its ends can be joined by a helical path of opposite twist but of greater pitch. Such a structure is diagrammatically presented in Fig. 8, where the track section 23| extends roughly 270 around the cam body 220 and is of relatively short pitch, while the track section 233 joining the ends of that section is of relatively long pitch and extends about 90 around the body. A block similar to 40 or |40 driven by a track of such form would travel at a uniform rate in each direction but at diierent rates in the two directions, and still with substantially instantaneous reversals.

The embodiments of the invention herein disclosed are illustrative and may be modified and departed from in various ways without departing from the spirit and scope of the invention as pointed out in and limited solely by the appended claims.

What is claimed is:

1. A cam mechanism element formed with a cam track having an angular portion, the said element comprising a body having a recess therein at the angular portion of the cam track, and two complementary members mounted in the recess and each formed with one side of the angular portion of the cam track up t0 the vertex thereof.

2. A cam mechanism element formed with a cam track having an angular portion, the said element comprising a body having a recess therein at the angular portion ofthe cam track, and two complementary members mounted in the recess and each formed with a part of the angular portion of the cam track and having the plane of separation of the two members passing through the vertex of the angle of the track.

VICTOR H. VAN SANT. 

